Wire spring assembly for seat structures



Nov. 15, 1966 E. H. GUTZMAN 3,285,598

WIRE SPRING ASSEMBLY FOR SEAT STRUCTURES Filed Sept. 21, 1964 5 Sheets-Sheet 1 INVENTOR ATTOf/Vf/S E. H. GUTZMAN WIRE SPRING ASSEMBLY FOR SEAT STRUCTURES Filed Sept. 21, 1964 Nov 15, 1966 5 Sheets-Sheet 2 a w m H a a. a v f MW ww m w 5 70/ W m w 4' my J-. 0 w m 7 wm j M d l A/J WE 9 IN VEN TOR.

fan Aw H. l/TZMA/V BY W Arrow/2 Nov. 15, 1966 5. H. GUTZMAN WIRE SPRING ASSEMBLY FOR SEAT STRUCTURES Filed Sept. 21, 1964 5 Sheets-Sheet 5 INVENTOR BY m M TWA Y5 United States Patent 3,285,598 WIRE SPRING ASSEMBLY FOR SEAT STRUCTURES Edward H. Gutzman, Georgetown, Ky., assignor to Hoover Ball and Bearing Company, Saline, Mich., a corporation of Michigan Filed Sept. 21, 1964, Ser. No. 397,810 Claims. (Cl. 267-107) This invention relates generally to upholstered seat structures and more particularly to an improved wire spring assembly for such structures.

United States Patent No. 2,480,667, assigned to the assignee of this application, shows -a wire spring assembly, of the type to which this invention relates, installed in a seat back. This type of spring assembly has proven to be advantageous because it is free of stiffness in localized areas and readily yields to loads when in use. When installed in a seat back, such an assembly comprises a plurality of upright face springs attached at their lower ends to a lower support rail, a support spring for each face spring which is mounted on the upper frame rail, and a border wire which is attached to at least the upper ends of the face springs. In order to improve the spring assembly shown in Patent No. 2,480,667, it is desirable to provide for a coaction of the face and support springs which either enables the use of more closely spaced face springs, without requiring additional total wire in the assembly, or enables the use of the same number of face springs involving a reduced amount of wire. In either case, the cost of the end product, namely, the seating structure, is reduced while maintaining the same or an improved seating comfort. If an increased number of face springs can be used without increasing the cost of the seating structure, the insulator pad which is normally interposed between the face springs and the upholstery for the purpose of uniformly transferring the seating load from the upholstery to the face springs can be eliminated with a consequent reduction in cost. It is an object of this invention, therefore, to provide an improved seat spring assembly for seating structures which incorporates the same desirable seating characteristics as the spring assemblies shown in Patent No. 2,480,667.

A further object of this invention is to provide an improved seat spring assembly which is economical to fabricate and assemble.

A further object of this invention is to provide an im- I proved spring assembly which enables the use of jointed border wire thereby making possible the provision of improved and unique seating results.

Another object of this invention is to provide an improved spring assembly for seat structures of the above type in which a single support spring supports a plurality of face springs thereby enabling the use of fewer support springs.

Still another object of this invention is to provide an improved spring assembly of the above type in which a single support spring supports a plurality of face springs and in addition constitutes extensions of the face springs and a section of a jointed border wire.

Further objects, features and advantages of this invention will become apparent from a consideration of the following description, the appended claims, and the accompanying drawing in which:

FIGURE 1 is a perspective view of a seat structure, showing spring assemblies of this invention incorporated in both the seat and seat back portions of the seat structure, with some parts of the structure broken away and other parts shown in section to better illustrate the construction of the spring assemblies;

3,285,598 Patented Nov. 15, 1966 FIGURE 2 is a vertical sectional view of the seat structures shown in FIG. 1, with the upholstery removed;

FIGURE 3 is a front view of a portion of the seat back spring assembly shown in FIGS. 1 and 2;

FIGURE 4 is a front view, illustrated similarly to FIG. 3, of a modified form of the spring assembly of this invention;

FIGURE 5 is a side view of the spring assembly shown in FIG. 4 showing the assembly mounted on a seat structure frame;

FIGURE 6 is a fragmentary front view of a portion of still another modified form of the spring assembly of this invention which is similar to the form of the invention illustrated in FIGS. 4 and 5;

FIGURE 7 is a front view, illustrated similarly to FIGS. 3 and 4, of still another modified form of the spring assembly of this invention;

FIGURE 8 is a side view of the spring assembly shown in FIG. 7 showing the assembly mounted on a seat structure frame; and

FIGURE 9 is a fragmentary from view showing an adaptation of any of the sring assemblies shown in FIGS. 4 to 8, inclusive, to an arrangement in which a nonjointed connection of the border wire sections is desired.

With reference to the drawing, one form of the spring assembly of this invention is illustrated in FIG. I mounted in both the seat and seat back portions of a seating structure 12. Each spring assembly consists of at least one and usually a plurality of spring units 10 arranged side by side, only one of which appears in both the seat and seatback structures illustrated in FIG. 1. The structure 12 has a back frame 14 which includes top and bottom vertically spaced rails 16 and 18 on which one spring assembly is mounted, and a seat frame 20 which includes front and rear frame rails 22 and 24 on which another assembly is mounted.

A spring unit 10 includes a plurality of face springs 26, namely, two in the illustrated embodiment of the invention, which are arranged side by side, a single support spring 28 and a border wire 30 secured to one end of each of the face springs 26. An adjacent unit 10 (FIG. 3) would be arranged so that the spacing between adjacent face springs 26 in adjacent units is substantially the same as the spacing between the face springs 26 in each unit 10.

Each of the face springs 26 is of a sinuous or corrugated shape having a plurality of transversely extending straight cross wire portions 32 connected by curved connecting wire portions 34. The face springs 26 are all of substantially the same length and have their cross 3 wire portions 32 at one end connected to spaced portions of the border wire 30 by clips 36. The cross wire portion 32 at the opposite end of each face spring 26 terminates in a laterally extending prong 38 which is adapted to be extended into a frame rail so as to support the face spring thereon. Each support spring 28 consists of a single piece of wire bent to form a connecting section 40 which lies in a plane parallel to and adjacent the inner sides of a pair of adjacent face springs 26, as shown in FIG. 2. As used herein, the inner side of a face spring 26 means the side inwardly of the seating structure 12. In the illustrated embodiment of the invention the support spring section 40 engages the upper end portions 42 of the face springs 26 in the seat back portion and the front end portions 42 of the springs 26 in the seat portion. The support spring 28 has the connecting section 40 formed so support spring 28. The spacing between the cross wires 44 and the cross wire 48 is evenly divisible by the spacing between adjacent cross wire portions 32 in the face spring 26. As a result, when thesupport spring connecting section 40 is positioned against one side of the section 42 of a face spring 26, the cross wires 44 and 48 are positioned side by side with cross wires 32 in the face springs 26. Clips 50 connect the cross Wires 44 to a first pair of face spring cross wire portions 32 in a pair of side-by-side face springs 26, and clips 52 similarly connect the cross wire 48 to another pair of cross wire portions 32.

The support spring 28 also has a support section 54 (FIG. 2) which is of substantially V-shape in vertical section through the seat structure 12 and is formed integral with the connecting section 40. The section 54 has a pair of spaced straight wire portions 56 which are integral with the remote ends of the cross wire portions 44 in the connecting section 48 and are inclined so as to constitute one leg of the V-shape section 54. A pair of axially aligned cross wires 58 extend inwardly toward each other from the ends of the wire portions 56 and constitute the apex of the V-shape supporting section 54. The other leg of the V-shape section 54 is formed by a pair of end portions 60 of the single piece of wire from which the spring 28 is formed. The end portions 60 are in a spaced parallel relation and extend at an angle to the wire portions 56. In addition the end portions 60 are overlapped, so that they form a U in developed plan (FIG. 3) and clips 62 connect the overlaps. A straight extension 64 of one of the end portions 60 constitutesan extension of the leg of the V formed by the end portions 60. The terminal end of the extension 64 is formed with a cross wire portion 65 which terminates in a prong 66. The prong 66 extends into the frame rail 16 so that the cross wire 65 lays against the rail 16, in the case of the seat back unit 10, and the rail 22 in the case of the seat unit 10.

It can thus be seen that the spring assembly of this invention consists of one or more side-by-side units each of which is comprised of a pair of sinuous face springs 26, a single support spring 28 having a connecting section 40 which is parallel to the outer end sections 42 of the face springs 26 and is secured 'by clips 50' and 52 to longitudinally spaced cross wire portion 32 of the face springs 26. Each support spring 28 has a V-shape connecting section 54 formed integral with the section 40 which flexes when the structure 12 is loaded so as to yieldably resist loads. In the assembly of a spring unit 10 with the back frame 14, the prong 66 at the terminal end of the support spring 28 is inserted in an opening in the upper frame rail 16. The prongs 38 at the terminal ends of the face springs 26 are similarly inserted in openings in the lower rail 18. In the assembly of a spring unit 10 with the seat frame 20, the prongs 66 are inserted in openings in the front frame rail 22 and the prongs 38 on the face springs 26 are inserted in openings in the rear frame rail 24. A border wire 30' connects the opposite ends of the face springs 26 in both installations to provide a firm edge support for the seat covering material which is mounted on the spring assemblies 10. The width of the seating structure 12 determines the number of sideby-side units 10 necessary on the back frame 14 and the seat frame 20.

Another form of the spring assembly of this invention is illustrated in FIGS. 4 and 5. This assembly likewise consists of one or more identical units, indicated generally at 10a, like the units 10 which are mounted on a seat frame to provide resilient resistance to load. Three units 10a are shown in FIG. 4, with only portions of two being illustrated since the three are identical. The unit 10a is similar to the assembly 10 previously described in that it includes a pair of side-by-side face springs 26a and a support spring 28a which is formed from a single piece of wire. The face springs 26a are formed of formed wire, which is similar to the sinuous wire from which the face springs 26 are formed in that it has straight cross wire portions 70 connected by connecting wire portions 72 which are generally straight, instead of curved as a in the case of sinuous wire, and the cross wire portions 70 may be unequally instead of evenly spaced. Formed wire and sinuous wire are generally known to be interchangeable in the seat spring art, and consequently the term zigzag wire or zigzag spring is used generically herein to include both sinuous and formed wire and springs. The face springs 26a are substantially identical and are formed at their inner ends with short cross wires 73 which terminate in prongs 74 and at their outer ends with return bent portions 76 which terminate short of the outer end of the unit 10a. Each return bent portion 76 is generally U-shaped having a pair of legs 77 which are spaced in a direction transversely of the face spring 26a for a purpose to appear presently. v

The single piece of wire which forms the support spring 28a is bent so that it has aligned cross wire end portions 78 which terminate in double prongs 79 for supporting the support spring 28a on a frame rail. The support spring 28a is formed so that in vertical section through a seat structure it has a V-shape supporting section 80 (FIG. 5) and an integral connecting section 82 which is positioned parallel to and adjacent the inner side of the face springs 26a. One leg of the V-shape section 80 is formed by spaced relatively inclined wires 81, which are integral with the cross wire end portions 78, and the other leg is formed by spaced wire 83 connected to the wires 81 by torsion bars 85. Cross wires 84, positioned in the connecting section 82, adjacent its juncture with section 80, are positioned parallel to and adjacent a pair of cross wires 70 in the face springs 26a and clips 86 are utilized to connect the cross wires 84 to the adjacent cross wires 70. The connecting section 82 also includes a pair of substsantially aligned cross wires 88 which extend inwardly toward each other and are connected to the cross wires 84 by leg wires 89. Each cross wire 88 is connected to the return bent portion 76 of a face spring 26a by positioning one leg 77 of the return bent portion 76 on one side of the cross wire 88 and positioning another leg 77 on the opposite side. As a result each face spring 26a in a pair is clampingly engaged at one end with a cross wire 88 in a connecting section 82 of the support spring 80.

In the unit 10a, the support spring 28a is formed with an extension 94 which extends outwardly from cross wires 88 and constitutes a section of a border wire and an extension of face springs 26a. Extension 94 includes a pair of face wires 95, which are spaced transversely of face springs 26a and are formed integral with cross wires 88, and terminates in a generally U-shape section 96 having a base wire 98 which constitutes a border wire section and short legs 100 disposed at opposite ends of base 98. The legs 100 are positioned side by side with the corresponding legs 100 in adjacent units 10a, positioned on opposite sides of the illustrated unit 10a and are connected thereto by wire clips 102. As a result a continuous border wire, like the border wire 30 illustrated in FIG. 3 is formed by aligned wire sections 98 in adjacent units 10a with the spring clips 102 constituting a pivotal connection between the adjacent border wire sections 98. As a result, a jointed border wire is provided in which one section 98 can move relative to others. In a seat assembly, a jointed border wire is desirable because it eliminates the effect of a load on one portion of the seating structure on another portion spaced therefrom. For example, when a couch is provided with a jointed border wire, formed as shown in FIG. 4, the tendency of a load on one portion of the couch to affect the seating characteristics of an adjacent portion is reduced. Consequently, a person sitting on such a couch has his comfort unaffected 'by others sitting down and getting up from other portions of the couch. The unit 10a is illustrated in FIG. 5 mounted on the back rails 16 and 18 for a seat structure 12, but it is to be understood that the unit 10a is also usable like the unit shown in FIG. 2 on the seat portion of the structure 12.

In FIG. 6 another form of the unit 10 is shown and indicated generally at 1012. The unit 10b is identical to the unit 10a in every respect except the shape of the face wires 95 in the extension 94 in unit 10a. Consequently, the same numerals are used on the unit 10b to indicate like parts on the unit 10a and only the extension 94 and adjacent parts of the unit 1012 are shown in FIG. 6. In unit 10b, the support spring 28b is formed with an extension 94 having face wires 101 provided with inclined portions 103 which extend toward each other and straight p0rtions105 which are adjacent each other and are connected by a spring clip 104. This arrangement of the clip 104 connecting the face wires 101 provides the border wire section 98 with increased rigidity in the unit 10b relative to its rigidity in the unit 10a. Consequently, a different seating effect is obtainable and the effect desired in a particular seating structure determines the choice of the unit 10a or the unit 10b.

Still another form of the spring unit of this invention is illustrated in FIGS. 7 and 8 and indicated generally at 100. The unit 100, which is similar to the units 10, 10a and 10b, includes a pair of face springs 26c, formed of sinuous wire, having cross wire portions 110 and connecting wire portions 112, and a support spring 28:: previously described in connection with unit 10a. The spring 28a is positioned so that its cross wires 84 and 88 are positioned adjacent and substantially parallel to a pair of cross wire portions designated 110a and 11% in each of the face springs 260. The cross Wire portion 110a in each spring is the endmost cross wire portion and the portion 11% is spaced therefrom. Clips 114 connect the cross wires 84 and 88 to the cross wire portions 110a and 11%. The unit 10c thus differs from the unit 10a only in the shape of the face springs and in the fact that each face spring is positively connected at a pair of longitudinally spaced points to the support spring 28a. The unit 100 also includes the border wire having the jointed sections 98, the advantages of which having been previously de scribed.

In the utilization of a spring assembly 10a, 1% or 100 constructed according to this invention, the jointed border wire feature may be undesirable at some locations in the seating structure. This undesirability may stem from a particular seating problem or from a particular problem connected with the application of the padding and the upholstery to the spring base. For example, at the front corner of a couch seat, it may be desirable to eliminate the jointed border wire feature in order to insure a neat and tight application of the upholstery covering. In such case, the extension 94 of the support spring which forms the border wire may be formed as indicated at 94a in FIG. 9 which illustrates a unit 10d which is similar in all other respects to the unit 10c. The extension 94a has legs 122 which converge as they leave the ends of the border wire section 98. A longitudinal overlap of adjacent border wire'sections 98, as shown in FIG. 9, is then provided. A spring clip 124 is utilized to connect the overlapping portions of the adjacent sections 98. Such an arrangement eliminates relative pivoting of adjacent border wire sections 120 and provides a non-jointed relatively continuous border wire for at least a portion of the spring assembly for the seating structure. Such a nonjointed arrangement is also obtainable in units 10a, 10b and 10c by merely lengthening sections 98 so that they overlap.

From the above description it is seen that this invention provides spring assemblies consisting of a plurality, namely two, face springs, and a single support spring therefor. These essential elements of the spring assembly are connected, as illustrated in U.S. Patent No. 2,480,667, so as to provide a yieldable suppont without any hard spots. The border wire may be attached to the terminal ends of the face springs, as shown in FIGS. 2

and 3, or the support spring may be provided with an extension which forms the border wire. This latter arrangement has the advantage of enabling a jointed border wire if such an arrangement is desired for a particular seating structure, and can in certain seating structures have a cost and weight advantage. The illustrated assemblies provide for versatility in seating structure designs since they enable a variety of seating characteristics. In any event, since a single support spring functions to support two face springs, the total amount of wire necessary to support the requisite number of face springs in a given seating structure is reduced thereby enabling either more face springs to thus eliminate the necessity for the usual insulator or other spring covering, or reduces the total cost of the seating structure with the same number of face springs.

It will be understood that the Wire spring assemblies for seat structures which are herein disclosed and described are presented for purposes of explanation and illustration and are not intended to indicate limits of the invention, the scope of which is defined by the following claims.

What is claimed is:

1. In a spring assembly for seating structures, a spring unit having a pair of ends one of which constitutes a mounting end, an inner side and an outer side, said unit comprising a plurality of longitudinally extending transversely spaced zigzag face springs and a single support spring for said face springs positioned on the inner side of said face springs, each of said face springs having a plurality of transversely extending cross wire portions and connecting wire portions extending therebetween, said support spring having a connecting section comprised of a pair of legs spaced in a direction transversely of said face springs, each of said legs having a pair of cross wire portions arranged adjacent a pair of face springs cross wire portions, means connecting longitudinally spaced cross wire portions of each face spring to a pair of adjacent cross wire portions in one of said legs, a V-shape mounting section integral with said connection section,

and a border wire section formed integral with said support spring and extending in a direction transversely of said face springs, said border wire being positioned longitudinally outwardly of said face springs at the end of said unit opposite said one end.

2. In a spring assembly for seating structures, a spring unit having a pair of ends one of which constitutes a mounting end, an inner side and an outer side, said unit comprising a plurality of longitudinally extending transversely spaced face springs and a single support spring for said face springs positioned on the inner side of said face springs, said support spring consisting of a single length of wire shaped to form a connecting section comprised of a pair of legs spaced in a direction transversely of said face springs, each of said legs having a pair of cross Wire portions, said length of wire having asubstantially straight intermediate portion which forms one cross wire portion in each of said pairs, means connecting the cross wire portions in each of said legs to longitudinally spaced portions of one of said face springs adjacent the end of said unit opposite said mounting end, and a V- shape mounting section integral at one end with said connecting section and terminating at the opposite end in a mounting prong formed at one end of said length of wire, said V-shape section having an apex and a pair of end portions of said length of wire extending from said apex toward said prong, said end portions being overlapped and connected together at a position between said apex and said prong, and means providing a border wire at the end of said unit opposite said one end.

3. In a spring assembly for seating structures, a plurality of spring units, each of said spring units having a pair of ends one of which constitutes a mounting end, an inner side and an outer side, said unit comprising a plurality of longitudinally extending transversely spaced face springs and a single support spring for said face springs positioned on the inner side of said face springs, said support spring having a connecting section supportingly connected to longitudinally spaced portions of each face spring and a V-shape mounting section integral with said connecting section, a border wire section formed integral with said support spring at the end of said unit opposite said one end and extending in a direction transversely of said face springs, said units being arranged side by side so that border Wire sections for said units are substantially aligned, and means connecting the border wire sections in adjacent units.

4. In a spring assembly for seating structures, a plurality of spring units, each of said spring units having a pair of ends, an inner side and an outer side, said unit comprising a plurality of longitudinally extending transversely spaced face springs and a single support spring for said face springs positioned on the inner side of said face springs, said face springs terminating at one end of said unit in mounting portions, said support spring having a connecting section supportingly connected to longitudinally spaced portions of each face spring and a V-shape mounting section integral with said connecting section, a border wire section formed integral with said support spring connecting section at the end of said unit opposite said one end and extending in a direction transversely of said face springs, each of said border wire sections being generally U-shape and having an elongated base portion and shorter leg portions at opposite ends of said base portion, said units being arranged side by side so that said base portions of the border wire sections for said units are substantially aligned and the leg portions for adjacent sections are side by side, and means pivotally connecting the leg portions in the border wire sections in adjacent units.

5. In a spring assembly for seating structures, a spring unit having a pair of ends one of which constitues a mounting end, an inner side and an outer side, said unit comprising a plurality of longitudinally extending transversely spaced zigzag face springs and a single support spring for said face springs positioned on the inner side of said face springs, each of said face springs having a plurality of transversely extending cross wire portions and connecting wire portions extending therebetween, said support spring having a connecting section comprised of a pair of legs spaced in a direction tranversely of said face springs, each of said legs having a pair of cross wire portions one of which is secured to an adjacent face spring cross Wire portion, each of said face springs terminating at the end of said unit opposite said mounting end in a return bent substantially U-shape portion having a pair of leg sections spaced transversely of said face spring and clampingly engaged with opposite sides of the other one of said cross wire portions in said support spring legs, a V-shape mounting section integral with said connecting section, and a border wire section integral with said support spring legs and extending transversely relatively to said face springs at the end of said unit opposite said one end.

6. A spring unit comprising a plurality of longitudinally extending transversely spaced zigzag face springs and a single support spring for said face springs positioned on the inner side of said face springs, each of said face springs having a plurality of transversely extending cross wire portions and connecting wire portions extending therebetween, said support spring having a connecting section comprised of a pair of legs spaced in a direction transversely of said face springs, each of said legs having a pair of cross wire portions one of which is secured to an adjacent face spring cross wire portion, each of said face springs terminating at one end in a return bent substantially U-shape portion having a pair of leg sections spaced transversely of said face spring and clampingly engaged with opposite sides of the other one of said cross wire portions in each of said support spring legs, a V-shape mounting section integral with said connecting section, an extension on said connecting section having face wires which constitute endwise extension of said face springs, and a border wire section integral with said face wires and extending transversely relatively to said face springs at the end of said unit opposite said one end.

7. A spring unit according to claim 6 in which said face wires are spaced in a direction transversely of said face springs.

8. A spring unit according to claim 6 in which said face wires are connected together at a position spaced from said border wire section.

9. A spring unit comprising a plurality of longitudinally extending transversely spaced Zigzag face springs and a single support spring for said face springs positioned on the inner side of said face springs, each of said face springs having a plurality of transversely extending cross wire portions and connecting wire portions extending therebetween, said support spring having a connecting section comprised of a pair of legs spaced in a direction transversely of said face springs, each of said legs having a pair of cross wire portions one of which is secured to an endmost face spring cross Wire portion, means securing a cross wire portion in each face spring which is spaced from said endmost cross wire portion to the other one of said cross wire portions in each of said support spring legs, a V-shape mounting section integral with said connecting section, an extension on said connecting section having face wires which constitute endwise extension of said face springs, and a border wire section integral with said face wires and extending transversely relatively to said face springs at the end of said unit opposite said one end.

10. A plurality of spring units constructed according to claim 9 and arranged in a side-by-side relation so that said border wire sections overlap, and means rigidly connecting overlapped portions of said border wire sections together.

References Cited by the Examiner UNITED STATES PATENTS 2,773,543 12/1956 Sandor 267l07 2,835,314 5/1958 Neely 267-107 2,849,057 8/1958 Neely 267107 3,095,189 6/1963 Slominski 267-107 ARTHUR L. LA POINT, Primary Examiner. 

1. IN A SPRING ASSEMBLY FOR SEATING STRUCTURES, A SPRING UNIT HAVING A PAIR OF ENDS ONE OF WHICH CONSTITUTES A MOUNTING END, AN INNER SIDE AND AN OUTER SIDE, SAID UNIT COMPRISING A PLURALITY OF LONGITUDINALLY EXTENDING TRANSVERSELY SPACED ZIGZAG FACE SPRINGS AND A SINGLE SUPPORT SPRING FOR SAID FACE SPRINGS POSITIONED ON THE INNER SIDE OF SAID FACE SPRINGS, EACH OF SAID FACE SPRINGS HAVING A PLURALITY OF TRANSVERSELY EXTENDING CROSS WIRE PORTIONS AND CONNECTING WIRE PORTIONS EXTENDING THEREBETWEEN, SAID SUPPORT SPRING HAVING A CONNECTING SECTION COMPRISED OF A PAIR OF LEGS SPACED IN A DIRECTION TRANSVERSELY OF SAID FACE SPRINGS, EACH OF SAID LEGS HAVING A PAIR OF CROSS WIRE PORTIONS ARRANGED ADJACENT A PAIR OF FACE SPRINGS CROSS WIRE PORTIONS, MEANS CONNECTING LONGITUDINALLY SPACED CROSS WIRE PORTIONS OF EACH FACE SPRING TO A PAIR OF ADJACENT CROSS WIRE PORTIONS IN ONE OF SAID LEGS, A V-SHAPE MOUNTING SECTION INTEGRAL WITH SAID CONNECTION SECTION, AND A BORDER WIRE SECTION FORMED INTEGRAL WITH SAID SUPPORT SPRING AND EXTENDING IN A DIRECTION TRANSVERSELY OF SAID FACE SPRINGS, SAID BORDER WIRE BEING POSITIONED LONGITUDINALLY OUTWARDLY OF SAID FACE SPRINGS AT THE END OF SAID UNIT OPPOSITE SAID ONE END. 